From 17834c6af4a9c59ced57dfeea0f7c1c48b771aa3 Mon Sep 17 00:00:00 2001 From: "Chia-Lin Kao (AceLan)" Date: Thu, 19 Mar 2026 11:14:17 +0800 Subject: [PATCH 2/3] xhci: Add debug instrumentation for VDEV_PORT_ERROR handling Add xhci_dbg() traces to the VDEV_PORT_ERROR set/clear path in handle_port_status() to validate the USB3-only guard added by: commit dbbaf9e5f422 ("xhci: restrict VDEV_PORT_ERROR to USB3 ports in handle_port_status()") The debug messages log: - When a USB3 port in SS.Inactive (PLS=6) sets VDEV_PORT_ERROR - When a USB3 port in SS.Inactive (PLS=6) skips VDEV_PORT_ERROR due to an active PORT_RESET - When PORT_RC clears VDEV_PORT_ERROR, including the port speed - When a USB2 port hits PLS=6 (reserved value), confirming the guard prevents incorrect VDEV_PORT_ERROR on USB 2.0 devices These traces help verify that Thunderbolt 4 docks with Realtek USB 2.0 hubs no longer trigger spurious VDEV_PORT_ERROR during the transient PLS=6 read that blocked URB queueing. Signed-off-by: Chia-Lin Kao (AceLan) --- drivers/usb/host/xhci-ring.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index bca44bc13ce75..38d64b5f0d4a4 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -2048,10 +2048,22 @@ static void handle_port_status(struct xhci_hcd *xhci, union xhci_trb *event) if (hcd->speed >= HCD_USB3 && vdev && (portsc & PORT_PLS_MASK) == XDEV_INACTIVE) { - if (!(portsc & PORT_RESET)) + if (!(portsc & PORT_RESET)) { + xhci_dbg(xhci, "port %d: USB3 SS.Inactive (PLS=6), no reset active, setting VDEV_PORT_ERROR\n", + port_id); vdev->flags |= VDEV_PORT_ERROR; + } else { + xhci_dbg(xhci, "port %d: USB3 SS.Inactive (PLS=6) with PORT_RESET active, skipping VDEV_PORT_ERROR\n", + port_id); + } } else if (vdev && portsc & PORT_RC) { + xhci_dbg(xhci, "port %d: PORT_RC set, clearing VDEV_PORT_ERROR (speed=%d)\n", + port_id, hcd->speed); vdev->flags &= ~VDEV_PORT_ERROR; + } else if (vdev && hcd->speed < HCD_USB3 && + (portsc & PORT_PLS_MASK) == XDEV_INACTIVE) { + xhci_dbg(xhci, "port %d: USB2 port with PLS=6 (SS.Inactive reserved), ignoring VDEV_PORT_ERROR (portsc=0x%08x)\n", + port_id, portsc); } if ((portsc & PORT_PLC) && (portsc & PORT_PLS_MASK) == XDEV_RESUME) { -- 2.53.0